With fast development of electrical and electronical technology, more and more modern mobile electronic products that use image sensor technology, such as smart phones, digital cameras, notebook computers, etc., have been rapidly developed and widely used. Currently, people spend significantly increased time on mobile phones and other electronic products and, tend to have more and more demands on product quality and personal experience. Today, most electronic devices are capable for snapping pictures and taking videos, and the total number of pixels in a camera has increased from the original several hundreds of thousands to five millions or even more. In electronic products, a major component for imaging is image sensor. Therefore, requirements on imaging quality of image sensors have become increasingly high.
Image sensor is a device to convert optical signals into electrical signals. Image sensor includes charge coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS) image transistor chip. Compared to traditional CCD sensor, CMOS image sensor demonstrates a number of advantages, such as low energy consumption, low cost, compatibility with CMOS technology, etc. Therefore, CMOS image sensor has become more popular. Specifically, CMOS image sensor has not only been used in the field of consumer electronics such as digital camera, cell phone camera, and camcorder, but also been widely used in the fields of automobile electronics, monitoring, biotechnology, and medical science, etc.
However, CMOS image sensors fabricated by existing methods may need to be further improved. Specifically, the fill factor in existing CMOS image sensors may be relatively small and noise (such as kTC thermal noise) may be generated during the operation of the CMOS image sensors.
The disclosed fabrication method and semiconductor structure are directed to solve one or more problems set forth above and other problems in the art.